1. Field of the Invention
This invention relates to a fuzzy controller, a fuzzy control system and a fuzzy control process which can be utilized for control of the flow rate and/or the pressure of a combustible gas, a supporting gas and a shielding gas in a burner used in the step of sealing a lamp glass pipe in a lamp manufacturing process, a combustion time control of the burner, a glass pipe seal abnormality diagnosis, and so on.
2. Description of the Related Art
Conventional lamp manufacturing processes require a special step at the time of enclosing electrodes in opposite end portions of a glass pipe of, for example, a quartz glass luminous tube of a discharge lamp, in which step a skilled operator sets optimal conditions for pressing the glass pipe ends so that foil portions of the electrodes are enclosed in optimal conditions by observing and judging the softened state of the glass pipe, the shape and light emitting state of the burner flame with the eyes.
That is, as conditions for the optimization of the softened state of the glass pipe for enabling the glass pipe to be sealed, the heating power of the burner, the state and characteristics of the flame and the period of time between the heating start time and the time at which the glass is softened to an extent such as to be suitable for being pressed are considered to be important. To set these conditions, therefore, a skilled operator judges the softened state of the glass pipe and the state of the burner flame from the shape and the light emitting state thereof with the eyes, presumes a cause of an abnormality by observing the state of the pressed sealed end portion of the glass pipe with the eyes, and weighs and suitably sets various parameters relating to the burner flame in the glass pipe sealing process, i.e., parameters of the control of the flow rate or the pressure of a combustible gas, a supporting gas, and a shielding gas, and parameters of glass sealing conditions, burner position control condition, and so on.
This conventional method will be described below in more detail with reference to FIGS. 6 to 13. FIG. 6 is a cross-sectional view of a glass pipe I in a state before being heated with a burner 6, FIG. 7 is a cross-sectional view in a direction perpendicular to the direction of FIG. 6, and FIG. 8 is a cross-sectional view taken along the line A--A of FIG. 7. As shown in FIGS. 6 to 8, a main electrode 2, an auxiliary electrode 3, molybdenum foil 4, lead wires 5 are inserted through an end portion of the glass pipe 1, while a temporary plug 20 (FIG. 13) is fitted in the pipe 1 at the other end, and the burner 6 is thereafter ignited to heat the glass pipe 1. As the end portion of the glass pipe 1 is heated and softened, a constricted portion 8 is formed as shown in FIGS. 9 (a), 9 (b) and 9 (c). The operator observes the shape of the constricted portion 8, the light emitting state of the glass pipe 1, the intensity and the color of the burner flame with the eyes to judge whether or not the conditions are suitable.
After a further predetermined period of time, mold parts 7 for pressing are automatically moved toward the glass pipe end by an air cylinder 14 (FIG. 13) to press the glass pipe end or reduce it in thickness so that the molybdenum foil 4 and the lead wires 5 are brought into close contact with the inner surface of the glass pipe end. The glass pipe end is thereby sealed. The molybdenum foil 4 is provided as intermediate portions of the leads 5 to enable the leads to be completely enclosed. The molybdenum foil 4 is welded to the leads 5. After the pressing, the operator observes the glass pipe end to judge whether or not the conditions are suitable from the existence/non-existence of defects, such as those shown in FIG. 12, i.e., creases 9 of a seal surface, press deficiencies A to D, and breaks 10 in the molybdenum foil 4.
With respect to causes of such defects, skilled operators know, from their experience, that the burner 6 heating time determining the extent to which the glass pipe 1 is softened by heating, the rate at which nitrogen gas is caused to flow to prevent the auxiliary electrode from being oxidized with oxygen in air when heated, and the force of pressing the mold parts 7 influence the occurrence of creases 9 of the seal surface and breaks in the molybdenum foil 4.
For example, in case where many creases 9 occur in the seal surface while breaks 11 occur in the welding portion between the lead wires and the molybdenum foil 4, the influence of the nitrogen flow rate is large. Also, the nitrogen flow rate relates strongly to the occurrences of breaks and oxidation of a central portion on the molybdenum fail 4. Similarly, if the effect of pressing is insufficient and if the burner time, i.e., the heating time is short, a void occurs in the portion B shown in FIG. 12. Conversely, if the burner heating time is excessively long, a tare deformation occurs such that the shape of the portion E shown in FIG. 12 is undesirable. If the burner position is so high that the glass pipe end heating position is not suitable, a press deficiency occurs at the portion D.
As described above, to prevent these defects, it is necessary to suitably set and control various conditions including the glass pipe end temperature, the nitrogen flow rate, the burner heating power, the glass pipe end heating position and the press pressure. According to the conventional method, a skilled operator examines the above-mentioned various defects with the eyes and determines control conditions for the glass pipe sealing step.
However, the above-described various conditions relate strongly to each other and automatization of the process of controlling them has been difficult. It has therefore been necessary that a skilled operator must obtain necessary information with the eyes and adjust the burner heating time from the heating start to the moment when a softened state of the glass pipe suitable for pressing is reached, the nitrogen flow rate (controlled with a valve V.sub.1 shown in FIG. 13), the burner heating power, i.e , the flow rate and the pressure of hydrogen and oxygen (controlled with valves V.sub.2 and V.sub.3 shown FIG. 13), the burner position, pneumatic pressure for controlling the pressure and speed of the press (controlled with an air cylinder 34 shown in FIG. 13) based on skilled operator's empirical knowledge which is difficult to express or hand down.
Moreover, it is very difficult for an unskilled operator to ascertain the caused of defect from the apparent condition of the sealed glass pipe because of the complex existence of the causes as well as the observation with the eyes. Also, it is very difficult even for a skilled operator to suitably judge the control conditions.
Because the sealing operation has been performed mainly by a manual control as described above, there have been the problem of retaining highly skilled operators, and the problem of the product qualities being varied depending upon the operators, so that the reliability of the manufacturing process is low. If glass pipes are manufactured while changing specifications with respect to glass pipe manufacture lots, the above-described adjustment must be performed each time of lot change, which is very troublesome. Also, it is necessary even for a skilled operator to repeat the readjustment operation many times to find optimum conditions, and this process is very time-consuming.